Both birds shown here are single factor males. The reason why they look so different is because the 'yellow' male has a white chest. It's hard to explain - Gouldian genetics are complicated!

Here's a pretty yellow hen.

Here's her again.

A young juvenile dilute male coloring out.

Kona's son, Junior.

A momma Gouldian and three of her babies.

My very first blueback male and a split to blue female (who unfortunately passed away after getting eggbound.) :(

This is a young white-breasted hen who's still coloring out.

A yellowback fledgling.

This is the yellowback fledgling, all grown up! His color is referred to a single factor yellow.

A handsome black headed male.

A young red head female.

Videos

In this first video, the male, Junior, is courting the hen, Kiwi. The hen is interested in the male, because she's standing close to him with her tail turned towards him. The only reason why she flies away is because the other birds scared her.